With such scanning near field microscopes, the tip of a rectilinear optical fiber probe maintained perpendicular to the sample is made to vibrate horizontally with respect to the sample surface and changes in the amplitude of vibrations occurring due to the shear force between the sample surface and the tip of the optical fiber are detected. Changes in the amplitude are detected by irradiating the tip of the optical fiber probe with laser light and detecting changes in the shadow of the tip. A gap between the tip of the optical fiber probe and the surface of the material is kept fixed by moving the sample using a fine-motion mechanism so that the amplitude of the vibrations of the optical fiber probe are constant, and the shape of the surface is detected and the optical permeability of the sample measured from the intensity of a signal inputted to the fine-motion mechanism.
There is also proposed (in Japanese Patent Publication Laid-open No. Hei. 7-17452) a scanning near field atomic force microscope where near field light is generated at the tip of an optical fiber probe as a result of introducing laser light into an optical fiber probe simultaneously with an AFM operation employing the pointed optical fiber probe as a cantilever for an atomic force microscope (hereinafter referred to as AFM) and the shape of the surface of a sample is detected and the optical characteristics of the sample are measured using the mutual interaction between the generated near field light and the sample. FIG. 12 is a side cross-section of a related example of an optical waveguide probe. This optical waveguide probe 110 employs an optical waveguide 101 as an optical fiber and the optical waveguide 101 is surrounded by a metal film 102. A pointed tip 103 is formed at one end of the optical waveguide probe 110 and a microscopic aperture 104 for generating near field light is provided at the end of the tip 103. The tip 103 is formed by bending the tip of the optical waveguide probe 110 around towards the sample (not shown).
Microcantilevers of the kind shown in FIG. 13 are well known in the related art (T. Niwa et al., Journal of Microscopy, vol. 194, pt. 2/3, pp. 388-392). At an optical microcantilever 120, an optical waveguide 111 is laminated from a core layer and a cladding layer and a metal film 112 is provided at the surface of the optical waveguide 111. A pointed tip 119 is formed at one end of the optical mircocantilever 120 and a support section 114 for fixing the optical microcantilever 120 is formed at the other end of the optical microcantilever 120. A microscopic aperture 113 for generating near field light is provided at the end of the tip 119.
The end of the optical microcantilever 120 at which the tip 119 is formed is referred to as the free end of the cantilever, and the optical waveguide end where the support section 114 is formed is referred to as the incident light end 117. The free end is bent in such a manner that the microscopic aperture 113 becomes in close proximity to the sample (not shown), and light propagated from the incident light end 117 enters the optical waveguide 111
An optical fiber guide channel 115 for fixing the optical fiber is formed at the support section 114. FIG. 14 shows the situation when an optical fiber 130 is fixed to the optical fiber guide channel 115. Light propagating from the optical fiber 130 enters the optical waveguide 111 via the incident light end 117 and is guided to the microscopic aperture 113 by the optical waveguide 111. Near field light is generated in the vicinity of the microscopic aperture 113 as a result of propagating light attempting to pass through the microscopic aperture 113. Conversely, near field light generated at the surface of the sample is scattered by the microscopic aperture 113 so as to generate propagating light and this propagating light can be detected at the incident light end 117 via the microscopic aperture 113 and the optical waveguide 111. Installation of the optical fiber 130 is straightforward because the optical fiber guide channel 115 is provided at the support section 114 and there is little trouble involved in aligning the optical microcantilever 120 and the optical fiber 130 during changing, etc.
However, productivity for the optical waveguide probe 110 is poor because the optical fiber 101 is employed as a material, which involves a large number of steps and is made manually. Further, even if the optical fiber 101 is covered in the metal film 102, propagating light loss occurs at locations where the optical fiber 101 is bent and light is therefore not propagated in an efficient manner, with this loss becoming more substantial as the angle of bending becomes more dramatic. Conversely, if the angle of bending is made smoother, the optical fiber probe becomes longer and handling therefore becomes more troublesome.
The optical microcantilever 120 has superior productivity and uniformity but loss of propagating light occurs at the optical waveguide 111 even when the metal film 112 is provided at the surface of the optical waveguide 111 and the propagating light cannot be propagated in an effective manner. In this manufacturing process, a smooth sloping surface 116 occurs between the incident light end 117 and the optical fiber guide channel 115 as shown in FIG. 14 and it is therefore difficult to get the optical fiber 130 sufficiently close to the incident light end 117 and the efficiency of the incident light is poor, i.e. coupling loss increases. Light is scattered at the incident light end 117 of the optical microcantilever 120 while light is made to pass through the incident light end 117 by the optical fiber 130 and scattered light also propagates in the direction of the microscopic aperture 113. This therefore causes the S/N ratio of a light image for the scanning type near field microscope to fall.
In order to resolve the aforementioned problems in the conventional art, it is an object of the present invention to provide an optical microcantilever bar capable of admitting and propagating light in an efficient manner, and a manufacturing method for making the optical microcantilever. It is a further object to provide an optical microcantilever holder for supporting the optical microcantilever bar and an optical element. It is a still further object to provide an optical microcantilever bar capable of improving an S/N ratio of a light image of a scanning near field microscope.